Linking sound production and dive behavior in feeding humpback whales

Abstract

Acoustic studies of baleen whales are becoming increasingly common. However, a minority of studies combines acoustic data with technologies that allow sound production to be placed in a detailed behavioral context. Noninvasive digital acoustic recording tags (DTAGS) were attached to humpback whales (Megaptera novaeangliae) on the western North Atlantic’s Great South Channel feeding grounds to study foraging and acoustic behavior. Acoustic records totaling 48.4 data hours from four attachments were aurally and automatically analyzed, and occurrences of several sound types were correlated with body orientation and dive behavior of the tagged subject. Whales produced a wide variety of sound types, which differed in depth and context of production. Long, tonal groans and moans (3-s average duration, 500-Hz peak frequency) occurred more frequently in upper portions of the water column, in contrast to broadband paired bursts (50-ms average duration, 300-Hz peak frequency), which appeared associated with bottom feeding. Virtual behavioral study using GEOZUI4D is used to visualize how sounds may be associated with foraging behavior. Overall results indicate sophisticated, situation-dependent use of sound. Behavioral implications of masking effects by surrounding vessel traffic noise are discussed.